Re: [PATCH V7 02/14] xfs: Check for extent overflow when trivally adding a new extent

[Allison Henderson <allison.henderson@xxxxxxxxxx>]

On 10/18/20 11:40 PM, Chandan Babu R wrote:
> When adding a new data extent (without modifying an inode's existing
> extents) the extent count increases only by 1. This commit checks for
> extent count overflow in such cases.

Looks ok
Reviewed-by: Allison Henderson <allison.henderson@xxxxxxxxxx>
> Reviewed-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
> Reviewed-by: Christoph Hellwig <hch@xxxxxx>
> Signed-off-by: Chandan Babu R <chandanrlinux@xxxxxxxxx>
> ---
>   fs/xfs/libxfs/xfs_bmap.c       | 6 ++++++
>   fs/xfs/libxfs/xfs_inode_fork.h | 6 ++++++
>   fs/xfs/xfs_bmap_item.c         | 7 +++++++
>   fs/xfs/xfs_bmap_util.c         | 5 +++++
>   fs/xfs/xfs_dquot.c             | 8 +++++++-
>   fs/xfs/xfs_iomap.c             | 5 +++++
>   fs/xfs/xfs_rtalloc.c           | 5 +++++
>   7 files changed, 41 insertions(+), 1 deletion(-)
>
> diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
> index d9a692484eae..505358839d2f 100644
> --- a/fs/xfs/libxfs/xfs_bmap.c
> +++ b/fs/xfs/libxfs/xfs_bmap.c
> @@ -4527,6 +4527,12 @@ xfs_bmapi_convert_delalloc(
>   		return error;
>   
>   	xfs_ilock(ip, XFS_ILOCK_EXCL);
> +
> +	error = xfs_iext_count_may_overflow(ip, whichfork,
> +			XFS_IEXT_ADD_NOSPLIT_CNT);
> +	if (error)
> +		goto out_trans_cancel;
> +
>   	xfs_trans_ijoin(tp, ip, 0);
>   
>   	if (!xfs_iext_lookup_extent(ip, ifp, offset_fsb, &bma.icur, &bma.got) ||
> diff --git a/fs/xfs/libxfs/xfs_inode_fork.h b/fs/xfs/libxfs/xfs_inode_fork.h
> index 0beb8e2a00be..7fc2b129a2e7 100644
> --- a/fs/xfs/libxfs/xfs_inode_fork.h
> +++ b/fs/xfs/libxfs/xfs_inode_fork.h
> @@ -34,6 +34,12 @@ struct xfs_ifork {
>   #define	XFS_IFEXTENTS	0x02	/* All extent pointers are read in */
>   #define	XFS_IFBROOT	0x04	/* i_broot points to the bmap b-tree root */
>   
> +/*
> + * Worst-case increase in the fork extent count when we're adding a single
> + * extent to a fork and there's no possibility of splitting an existing mapping.
> + */
> +#define XFS_IEXT_ADD_NOSPLIT_CNT	(1)
> +
>   /*
>    * Fork handling.
>    */
> diff --git a/fs/xfs/xfs_bmap_item.c b/fs/xfs/xfs_bmap_item.c
> index 9e16a4d0f97c..1610d6ad089b 100644
> --- a/fs/xfs/xfs_bmap_item.c
> +++ b/fs/xfs/xfs_bmap_item.c
> @@ -497,6 +497,13 @@ xfs_bui_item_recover(
>   	xfs_ilock(ip, XFS_ILOCK_EXCL);
>   	xfs_trans_ijoin(tp, ip, 0);
>   
> +	if (bui_type == XFS_BMAP_MAP) {
> +		error = xfs_iext_count_may_overflow(ip, whichfork,
> +				XFS_IEXT_ADD_NOSPLIT_CNT);
> +		if (error)
> +			goto err_cancel;
> +	}
> +
>   	count = bmap->me_len;
>   	error = xfs_trans_log_finish_bmap_update(tp, budp, bui_type, ip,
>   			whichfork, bmap->me_startoff, bmap->me_startblock,
> diff --git a/fs/xfs/xfs_bmap_util.c b/fs/xfs/xfs_bmap_util.c
> index f2a8a0e75e1f..dcd6e61df711 100644
> --- a/fs/xfs/xfs_bmap_util.c
> +++ b/fs/xfs/xfs_bmap_util.c
> @@ -822,6 +822,11 @@ xfs_alloc_file_space(
>   		if (error)
>   			goto error1;
>   
> +		error = xfs_iext_count_may_overflow(ip, XFS_DATA_FORK,
> +				XFS_IEXT_ADD_NOSPLIT_CNT);
> +		if (error)
> +			goto error0;
> +
>   		xfs_trans_ijoin(tp, ip, 0);
>   
>   		error = xfs_bmapi_write(tp, ip, startoffset_fsb,
> diff --git a/fs/xfs/xfs_dquot.c b/fs/xfs/xfs_dquot.c
> index 1d95ed387d66..175f544f7c45 100644
> --- a/fs/xfs/xfs_dquot.c
> +++ b/fs/xfs/xfs_dquot.c
> @@ -314,8 +314,14 @@ xfs_dquot_disk_alloc(
>   		return -ESRCH;
>   	}
>   
> -	/* Create the block mapping. */
>   	xfs_trans_ijoin(tp, quotip, XFS_ILOCK_EXCL);
> +
> +	error = xfs_iext_count_may_overflow(quotip, XFS_DATA_FORK,
> +			XFS_IEXT_ADD_NOSPLIT_CNT);
> +	if (error)
> +		return error;
> +
> +	/* Create the block mapping. */
>   	error = xfs_bmapi_write(tp, quotip, dqp->q_fileoffset,
>   			XFS_DQUOT_CLUSTER_SIZE_FSB, XFS_BMAPI_METADATA, 0, &map,
>   			&nmaps);
> diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
> index 3abb8b9d6f4c..a302a96823b8 100644
> --- a/fs/xfs/xfs_iomap.c
> +++ b/fs/xfs/xfs_iomap.c
> @@ -250,6 +250,11 @@ xfs_iomap_write_direct(
>   	if (error)
>   		goto out_trans_cancel;
>   
> +	error = xfs_iext_count_may_overflow(ip, XFS_DATA_FORK,
> +			XFS_IEXT_ADD_NOSPLIT_CNT);
> +	if (error)
> +		goto out_trans_cancel;
> +
>   	xfs_trans_ijoin(tp, ip, 0);
>   
>   	/*
> diff --git a/fs/xfs/xfs_rtalloc.c b/fs/xfs/xfs_rtalloc.c
> index 9d4e33d70d2a..3e841a75f272 100644
> --- a/fs/xfs/xfs_rtalloc.c
> +++ b/fs/xfs/xfs_rtalloc.c
> @@ -804,6 +804,11 @@ xfs_growfs_rt_alloc(
>   		xfs_ilock(ip, XFS_ILOCK_EXCL);
>   		xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
>   
> +		error = xfs_iext_count_may_overflow(ip, XFS_DATA_FORK,
> +				XFS_IEXT_ADD_NOSPLIT_CNT);
> +		if (error)
> +			goto out_trans_cancel;
> +
>   		/*
>   		 * Allocate blocks to the bitmap file.
>   		 */